A switch disconnector is an electrical high-voltage switch with low current switching capacity for high-voltage systems. It usually has switching error protection which prevents inadvertent opening and closing under load. In the event of a switching operation under load, a known switch disconnector would be damaged due to the arc which would occur.
C and O switching capacity means that the switch so designated, in the present case a switch disconnector, provides a switching capacity to be specified within a C or O circuit. This switching capacity is determined by the switching speed.
Now back to the actual switch disconnector, which, as already explained, is used as an electrical high-voltage switch with limited current switching capacity for high-voltage systems or high-voltage switchgear systems. Circuit breakers or load isolating switches with high current switching capacity, which, as a rule, are combined in series with the switch disconnector, can be specified to isolate the electrical connection under load.
Accordingly, although, as intended, switch disconnectors are actuated exclusively when circuit breakers are open, as a result of the control capacitances over the circuit breaker switching paths, that is to say the capacitance of the connected parts of the network, the compensating currents associated with these capacitances have to be switched on and off.
Switch disconnectors are therefore designed for a minimum switching capacity, so that, when switching capacitive busbar currents, inductive currents of transformers on no load and also during bus current transfer switching, the arc contacts of the pin contacts of the switch disconnector do not wear or at least do not wear too quickly, for example, as transient overvoltages which promote the formation of arcs are produced as a result of rupturing the arc at alternating frequencies.
The switching time of a known motor drive for the switch disconnector is approximately 1 second, for example, and the switching speed is approximately 0.1 m/s. As a result of the duration of the arc when capacitive busbar currents are switched, inductive currents of transformers on no load and also during bus current transfer switching, the arc contacts of the disconnector pins are subject to wear. For these reasons, the switching of transformers operating on no load has previously only been possible using a high-speed circuit breaker (transformer panel).
On the other hand, as a consequence of its very short arcing times, a high-speed switch disconnector can avoid this disadvantage and, when correctly rated, is suitable for switching transformers on no load. It therefore replaces a circuit breaker.
Starting from this prior art, exemplary embodiments of the present disclosure specify a switch disconnector that is optimized with regard to its switching behavior for a fast switching capacity and can be produced in a simple manner and with little effort.